Ion Channels and Neuronal Excitability

These flashcards cover the fundamental principles of neuronal communication, types of ion channels, the sodium/potassium pump, and the generation of resting membrane potentials and action potentials.

Electroencephalography (EEG)

A technique used to measure the electrical impulses produced by the brain.

Electrical currents (in neurons)

Driven by the movement of positively and negatively charged ions inside and outside of the cell membrane, resulting in a potential difference measured in $mV$.

Ion channels

Integral membrane proteins that form pores selective for specific ions ($Na^+$, $K^+$, $Ca^{2+}$, $Cl^-$), facilitating their movement across the hydrophobic lipid bilayer.

Electrical gradient

A driving force where negative ions move towards positive charges and positive ions move towards negative charges.

Chemical gradient

A powerful force of diffusion where ions move from an area of higher concentration to lower concentration to reach equilibrium.

Leak channels

Ion channels that do not require a stimulus and can open or close randomly at different times.

Ligand-gated channels

Channels activated by the binding of a chemical ligand to a specific protein subunit, such as $GABA_A$ and $NMDA$ receptors.

Mechanically-gated channels

Channels that open and close in response to a mechanical stimulus, such as stretch sensors.

Voltage-gated channels

Channels activated by membrane depolarisation which contain a voltage sensor at the bottom of the channel.

Sodium/potassium pump

A membrane-embedded protein that uses $ATP$ to transport $3,Na^+$ outside and $2,K^+$ inside the cell to maintain concentration gradients.

Resting membrane potential

A stable state typically reached at $-70,mV$ across the membrane, which is vital for the generation of electrical impulses.

Action potentials

Also known as nerve impulses or spikes, these are electrical signals whose frequency and pattern represent a code for information transfer.

Inhibitory postsynaptic potentials (IPSP)

Small electrical currents that tend to make the postsynaptic neuron more negative, a process known as hyperpolarisation.

Excitatory postsynaptic potentials (EPSP)

Small electrical currents that tend to make the postsynaptic neuron more positive, a process known as depolarisation.

Axon hillock

The specific region of a neuron where an action potential is generated if sufficient depolarisation occurs.